1. Field of the Invention
This invention relates to an improved vehicular proximity sensing system which is useful for alerting the driver of a motorized vehicle to the unduly close approach of a foreign object. Such systems are useful on the highway to reduce the risk of dangerous tailgating or to warn of the risk of sideswiping and, when equipped with audible warning means, may serve to awaken a sleepy driver wandering off-course in time to avert an accident.
A good proximity sensing system with sensitive close range detection is also valuable in parking situations, especially to help drivers with poor depth perception, or to alert the driver to the risk of collision with a more or less out-of-sight object such as a post or high kerb.
2. The Prior Art
Such useful vehicular proximity sensing systems are described and shown in my U.S. Pat. Nos. 3,842,397 and 4,015,232. These patents disclose a vehicular proximity sensing system to detect the relative approach of an external object to a motorized vehicle, the system having a plurality of reflectable energy transmitting-receiving distance-detecting devices disposed around the vehicle's periphery, and driver-alert means responsive to signals received from the distance-detector devices to alert a driver to close approach of the vehicle to the external object.
Clearly, for the purposes of the design of such a system, it is not important whether the external object is moving or the vehicle itself is moving: all that is of interest is relative movement between the two. Thus the external object can be another vehicle on the highway, such as a car, a tailgating truck or a slow-moving highway work vehicle or indeed a not readily visible stationary object such as a barrier for a construction diversion.
In my earlier patents I used ultrasonic energy signals as the reflectable energy and this provided a sensitive system that was effective for the purposes described. However, in the thirteen years that have passed since the issuance of '232 I have conducted substantial research directed towards further developing my systems to be suitable for mass production and widespread utilization as original equipment on a large number of vehicles, as well as for retrofitting to existing vehicles, and to provide useful features that were not previously envisaged.
During the course of my research it has become apparent that one of the problems associated with the large scale utilization of a vehicular proximity sensing system is the potential for false positives which may distract or annoy the driver and cause him to ignore or stop using the system.
In spite of their obvious merits, to my knowledge, vehicular proximity sensing systems have not been adopted as original equipment, and certainly have not come into general use, as have other accident avoidance systems, for example antilock brake systems and automatic air bags.